How did Mount Etna support Charles Lyell's geological ideas?

Mount Etna provided critical evidence for Charles Lyell’s theory of uniformitarianism, which posits that Earth's features are shaped by gradual, ongoing natural processes rather than sudden, cataclysmic events.123

During his explorations in Sicily, Lyell observed the geological structure of Mount Etna and concluded that the mountain was formed by the accumulation of repeated, small volcanic eruptions over a vast period of time. This observation directly countered the prevailing "catastrophist" view held by some of his contemporaries, who insisted that such massive landforms must have been created by sudden, violent upheavals.43

By demonstrating that even a prominent volcanic feature could be explained by the same slow, consistent processes observable in the modern world, Lyell provided a powerful, empirical validation for his uniformitarian principles. These findings were instrumental in the development of his seminal work, Principles of Geology, which fundamentally shifted the scientific understanding of Earth's history and age.235